1. Technical Field
The present invention relates to a feed controller attached to a battery holder of a battery drive type device to control power supply to battery load.
2. Related Art
According to a technology currently proposed for a battery drive type device such as a camera to which a plurality of batteries are attachable, power is supplied to a load not by using all the attached batteries but supplied to only a main load via a secondary battery as a main power source, for example, while monitoring the remaining capacity of the secondary battery. When the remaining capacity becomes smaller than a predetermined value, electromotive force of a primary battery separately attached is boosted by a boosting circuit and supplied to charge the secondary battery (see JP-A-10-68978, paragraph 0033, FIG. 5).
In addition, a technology of co-using an optical communication device which uses flickering of a display unit as a communication device not easily affected by external noise has been proposed in the field of portable information terminal such as cellular phone and PDA (personal digital assistant) as a battery drive type device.
According to this technology, the function of the optical communication can be added only by using appropriate algorithm without necessity for addition of other separate device (see JP-A-2005-12754, paragraphs 0009-0011, FIG. 1).
According to the technology disclosed in JP-A-10-68978, the plural batteries occupying not a small space in the battery drive type device are provided to make up for decrease in the electromotive force of the device so that operation time of the battery drive type device such as a camera can be extended without charge from the outside or replacement of the batteries with new ones. However, the batteries function only as power source, and thus do not provide expansion and variation of the function of the device.
According to the technology disclosed in JP-A-2005-12754, the function of the optical communication can be added only by using appropriate algorithm. However, the distance of the light emission from the display unit of the portable information terminal is limited, which makes it difficult to provide longer communication distance currently demanded.